1. Field of the Invention
The present invention relates to an index printer, and more particularly to an index printer which effects density correction using a standard image.
2. Description of the Related Art
Conventionally, an image printing apparatus, in which images recorded on a developed negative film are printed and developed onto a photographic printing paper so as to be able to obtain a photographic print, is well-known. In this type of image printing apparatus, conditions of exposure can be reset such that an appropriate photographic print is always obtained. In a case in which the conditions of exposure are set for such an image printing apparatus, a so-called Bull's eye, on which a gray image is recorded, is used. The Bull's eye is printed onto the photographic printing paper so as to obtain a test print. On the basis of the density of the test print, a color balance, a slope and the like ire adjusted and the conditions of exposure are corrected. The appropriate print, which corresponds to the image recorded on the photographic film, can be obtained by the reference amount of exposure determined by this correction.
On the other hand, in recent years, an index print in which frames are printed in a matrix has been proposed such that pictures photographed on a piece of developed film can be easily searched. A well-known example of an index printer which can produce such an index print is an index printer, in which a liquid crystal panel is used as image displaying means, a plurality of image frames recorded on the photographic film are displayed once on a display surface of the liquid crystal panel, and the images are simultaneously printed onto the photographic printing paper as the images smaller than those of the ordinary print.
In order to obtain appropriate images at the above-described index printer, it is necessary to set exposure conditions of the index printer similarly to an ordinary image printing apparatus. In this case, the image data obtained at the time of producing the main print (or ordinary print) can be used as it is at the index printer. Because a light source used at the time of producing the main print is different from the one used at the time of producing the print of the liquid crystal image, it suffices if the difference in densities is adjusted. At this time, the Bull's eye is used for correcting the difference in densities similarly to the correction of conditions of exposure for main print.
However, if the previously-described Bull's eye for adjusting the amount of exposure is used as it is at the index printer, there is a case in which the frame portion which displays the Bull's eye deviates from the center of the display screen such that the gray image does not exist at the center of the photographic printing paper. Unless the gray image is displayed at the center of the photographic printing paper, the density cannot be measured by a densitometer which is disposed so as to measure the density of the center of the photographic printing paper. Moreover, the position of the image frame on the index print can be altered such that the image frame which corresponds to the gray image is disposed at the center of the photographic printing paper. However, since the image is printed with the size of the image frame being reduced as compared to the size of an ordinary print, the size of the frame is small, and therefore, mistakes in reading the image can occur.